1. Field of the Invention
This invention relates to a clamping and cutting mechanism, particularly a mechanism for clamping an umbilical cord at two spaced points, cutting the cord between the two clamp points, and partially unclamping one of the severed cord sections so that blood samples can be taken.
2. Prior Developments
In the practice of delivering a newborn infant it is necessary to sever the umbilical cord, i.e. a tubular membrane containing the arteries and vein which supply oxygen and nutrient enriched blood from the mother to the fetus and which carries waste products from the fetus back to the mother. As blood flows through the umbilical cord,it is essential that the cord be sealed on both sides of where it is to be severed before any cutting takes place. The conventional method to clamp and cut the umbilical cord is a four step procedure. To accomplish this task the doctor must clamp one hemostat (a locking scissors like instrument) onto the umbilical cord, obtain another hemostat and clamp it on the cord a few inches away. After the two clamps are set, the doctor obtains a pair of scissors and warns the staff that he/she is about to cut so that they can avoid being sprayed by blood. The doctor then cuts the cord between the two clamps with a pair of scissors.
When the two hemostats are locked onto the cord, a bubble of blood forms in the segment of cord between the two clamps. When this segment is cut, blood tends to spray and often strikes the medical staff. Clamping and cutting the umbilical cord by the conventional method while trying to hold a slippery squirming infant in gloved hands can prove to be a challenge. If the infant has any abnormalities or health problems, the procedural difficulties are magnified, making speed and efficiency critical.
After the cord has been cut the number of arteries and veins in the cord are counted, and blood samples are obtained from the mother's end of the cord. In order to count the number of arteries and veins the doctor simply looks at the free end of the cord. If the end of the cord does not have a clean cut, it is sometimes necessary to make another cut in the cord in order to get a better view. The blood sample is obtained from the cord by placing a test tube in alignment with the free end of the cord and opening the hemostat enough to allow blood to flow into the test tube. During this procedure blood often sprays on the medical staff due to the cord slipping out of the jaws of the hemostat or by mis-direction of the artery when the hemostat jaws are opened. After enough blood is obtained, the hemostat is reclamped. The hemostat stays attached to the umbilical cord until after the placenta is extracted from the mother. The hemostat on the infant end of the umbilical cord is replaced by a disposable plastic clamp which stays with the baby until the umbilical cord falls off.
It is the object of the present invention to speed up the clamping and cutting procedure in order to provide the doctor with more time to focus on and administer to the needs of the patients and to protect the medical staff from blood transmitted disease such as H.I.V. and Hepatitis. The present invention includes a clamp section system design so that when it is compressed around the umbilical cord the cord is clamped in two places; both clamps are locked closed before any cutting takes place, and the blood is squeezed out of the clamped-off section to eliminate the possibility of blood become air borne when the cord is cut. The blade is concealed in the body of the mechanism to eliminate the possibility of anyone being injured by the blade. The mechanism of the present invention is designed so that it can be used to draw blood from the cord in a controlled manner, and to provide a cleanly severed end on the fetal side of the umbilical cord, with sufficient length to view the number of arteries and veins in the cord.
In the recent past, various umbilical cord clamping and cutting devices have been designed to speed up the clamping and cutting process. Known devices intended to perform cutting and clamping tasks are disclosed in U.S. Pat. Nos. 5,190,556, Hessel, 5,127,915, Mattson, 5,009,657, Cotey et al, 4,870,965, Jahanger, and 4,648,401, Mattson. None of these insure that the cord is fully sealed before cutting begins, or that the cord will not slide out when cutting without puncturing the cord. Also, U.S. Pat. Nos. 4,938,215 Schulman et al., 4,856,517, Collins et al., 4,781,188, Collins et al., 4,781,188, Collins, 4,716,886, Schulman et al, 4,572,181, Mattler, 4,428,374, Auburn, 4,026,294, Mattler, 3,631,858, Ersek, 3,323,208, Hurley, 3,166,071, Mayer, 3,106,919, Churchville, 2,524,337, Whittaker, and 2,060,724, Carrol all show umbilical cord clamp and cutting devices. Of these Patents, none allow the maternal clamp to be opened for the taking of blood samples. The devices of these patents have generally failed to meet all of the needs of the doctor and the patients.
U.S. Pat. No. 4,212,303, issued to John Nolan on Jul. 15, 1980, discloses an umbilical cord clamp that comprises two clamp arms hingedly connected together for closure on the cord. The free end of one clamp arm has a deflectable tongue that is lockable in a recess in the free end of the other arm when the clamp arms are closed on the umbilical cord.
U.S. Pat. No. 4,716,886 to Schulman et al, discloses an umbilical cord cutting device that includes two similarly constructed clamps connected together by a shear pin. A cutting blade is floatably positioned between the clamps so that when the clamps are clamped to the umbilical cord the blade can be moved through the space between the clamps to sever the cord and the shear pin, thereby separating the clamps.
U.S. Pat. No. 4,856,517, issued to J. Collins et al on Aug. 15, 1989, discloses an umbilical cord cutter mechanism that include a holder containing a cutter blade and two detachable clamps on opposite sides of the blade. Each clamp has latch means for holding the clamp in the closed position when the holder is closed to operate the blade. The holder can be removed from the clamps after the cord severing operation.
There is apparently no provision in the device of U.S. Pat. No. 4,856,517 for partially loosening either clamp to withdraw a blood sample from one of the severed cord sections.
U.S. Pat. No. 4,870,965, issued to M. Johanger, discloses an umbilical cord severing mechanism wherein a scissors cutter has a first cord clamp affixed to the cutter structure, and a second fetal cord clamp detachably mounted in the cutter structure, whereby the fetal clamp is ejected during the cutting stroke. A leaf spring in the cutter structure acts as an ejector device. The cutting action is achieved by two blade elements carried by the opposed jaws of the scissors structure.
One disadvantage of the patented structure is that the blades begin the cutting operation before the umbilical cord is fully clamped in the two clamp mechanisms. Also, there is no provision for relaxing the clamp pressure on the severed cord to facilitate drawing a blood sample.
U.S. Pat. No. 5,009,657, to J. Cotey et al, shows an umbilical cord cutting mechanism that includes a jaw structure having an integral cutter blade and a separable fetal chord clip. The jaw structure includes a hinge structure that has a lug that normally holds the fetal chord clip in the jaw structure; when the jaw structure is closed the lug is displaced so that the fetal chord clip can separate from the jaw structure.
U.S. Pat. No. 5,127,915 to P. D. Mattson, discloses a scissors type instrument for cutting an umbilical cord, said instrument having a detachable clamp structure equipped with a latch means so that after the cord is severed the clamp remains attached to the infant end of the cord. The scissors type instrument can be removed from the clamp structure after the cord-severing operation.
One disadvantage of the arrangement of U.S. Pat. No. 5,127,915 is that the cord is clamped at only one point along the cord surface; the cord is thus not fully compressed in the immediate vicinity of the cutting plane so that there is a danger of blood spurting from the unclamped end of the cord. The unclamped end of the severed cord is not sealed.